1. Field of the Invention
The present invention generally relates to encapsulants for use in window assemblies.
2. Description of the Related Art
Polymeric encapsulants for window assemblies are generally known in the art. Generally, window assemblies include a transparent pane, commonly made from glass. A ceramic frit is typically disposed about a perimeter of the transparent pane by methods commonly known in the art, like printing the ceramic frit on the transparent pane. The polymeric encapsulant is bonded to the perimeter of the transparent pane. The encapsulant can be bonded to one, two, or three surfaces of the transparent pane, and is typically bonded to the transparent pane via a primer. Said differently, the encapsulant bonds to the primer, which is bonded to the transparent pane, thereby bonding the encapsulant to the transparent pane.
Generally, the encapsulant can be either a thermoset material or a thermoplastic material. Exemplary thermosetting materials include, for example, a reaction injection molded (RIM) material, while exemplary thermoplastic polymer include materials such as polyvinylchloride (PVC) or a thermoplastic elastomer (TPE). While such conventional thermosetting or thermoplastic encapsulants are generally suitable for their intended purpose, they do suffer from a variety of known deficiencies.
For example, in prior art window assemblies utilizing conventional encapsulants such as TPE, it was generally not thought possible to seal the window assembly to the vehicle body by application of an adhesive material directly to the encapsulant because the adhesive material would not bond to such encapsulant. As a result, to couple the window assembly to the vehicle body, depending upon the type of polymer utilized, the adhesive material was applied to an exposed portion of the transparent pane and coupled to the vehicle body. Alternatively, metallic studs concealed within the encapsulant could be utilized. As one of ordinary skill would appreciate, such an arrangement limits the possible design variations for window assemblies, as a portion of the transparent pane located in close proximity to the vehicle body would necessarily need to be available for adhesive bonding.
In addition, conventional encapsulants such as TPE are generally not thought to be structural in nature. Thus, they are not strong enough to support or encapsulate window assembly support members, such as studs or rails. This also may limit possible design choices for window assemblies.
Further, conventional encapsulants such as RIM are relatively expensive to produce, requiring significant capital expense in terms of production equipment. In addition, there are also costs associated with the handling potentially hazardous components such as isocyanates used to form RIM encapsulants.
While PVC encapsulants are relatively inexpensive to produce, they are also chlorinated and thus are not considered environmentally friendly. In addition, special handling may be required with respect to recycling.
The present invention addresses many of these known deficiencies.